Electrical receptacle with safety shutter



Oct. 31, 1950 l. MosEs, JR., ETAT.

ELECTRICAL RECEPTACLE WITH SAFETY SHUTTER Filed July 5l, 1948 JR. sHAHADY ESA ALBERT. BY

IN VEN TORS.

\SAAC MDSES I} l l l l l l l l L l Y l I l l l l l l u 1 illbua. IlA

fn/0&9 9 ATTORNEYS.

Patented Oct. 3l, 1950 ELECTRICAL RECEPTACLE WITH SAFETY SHUTTER Isaac Moses, Jr., and Shahady Esa Albert, New Kensington, Pa.

Application July 31, 1948, Serial No. 41,875

Our invention relates to electric receptacles such as are installed in walls, baseboards, etc., and which serve as means whereby an electric appliance may be connected by a cord and plug to live wires and more particularly to what is known as a safety receptacle in which it isdiflicult or impossible to make accidental contact with the live parts of the receptacle.

The electric receptacle made according to our invention is adapted to receive any standard plug, or it may be constructed, if so desired, to receive any special plug. The arrangement is such that a shutter or barrier is positioned so that it is impossible to reach the live contacts until the two prongs of the plug are inserted into the prong slots and the shutter then moved so that the plug prongs may be slid further into the receptacle to contact engaging position. When the plug is withdrawn, the shutter member will return to barrier position and prevent engagement with the contacts by means of a foreign single piece of conducting material such as a wire or hairpin which may be inserted into the ordinary receptacle to engage a live contact, and which may cause grave results;

Our invention provides two locks for the shutter when in barrier position, which locks must be both released simultaneously to enable the shutter to be moved from the barrier position,

which is such that it is impossible to move the'A prongs of a plug into engagement with the live contacts of the receptacle, to a position whereby f the live contacts may be engaged by two prongs of a proper size and spacing, such as are found on standard insertable plugs.

It is one of the objects of our invention to Vprovide a receptacle in which the live contacts cannot be engaged except by an object having two prongs of a determined size and spacing.

It is another object to provide a receptacle'- wherein contact with a current-carrying portion thereof can be made only by a two-step operation performed in a denite manner.

It is a further object to provide a receptacle having a barrier which may be released for movement only by the simultaneous action of two prongs of a desired plug.

It is still another object of our invention to provide a receptacle having a barrier which will return to a protecting position as soon as the prongs of the insertable prongs of the plug are withdrawn from the receptacle.

4 Claims. (Cl. 173-330) certain presently preferred embodiment of our invention:

Figure 1 is a front view in elevation of a receptacle, but without the cover plate, embodying our invention;

Figure 2 is a front view in elevation showing the receptacle with the cover plate in position;

Figure 3 is a side view in elevation of the receptacle shown in Figure 1, with the cover plate in position, and showing in dotted lines a standard insertable plug with its two prongs in position to unlock the receptacle;

Figure 4 is a view generally similar to that shown in Figure 3, but showing the insertable plug in position with its two prongs engaging the live electric contacts of the receptacle;

Figure 5 is a View in cross section along the line V-V of Figure 1; and

Figure 6 shows a form of insertable plug which may be used with our receptacle.

Our receptacle is adapted to receive any standard plug having two connection prongs which may be inserted by pushing the prongs into apertures prepared for it in a barrier plate to release two locking dogs which engage the barrier or shield plate, whereupon the plug may be raised to move the barrier to a position where the prongs may be inserted further into the receptacle to engage the usual live electrical contacts therein. When the prongs are pulled out ofr the receptacle, the barrier plate is then moved by springs to a position where the locking dogs engage the barrier plate, in which position the apertures in the barrier position are out lof alignment with the contacts. This makes it impossible for any one to engage the electrical contacts by means of an instrument having only-*a single prong-like member. Thus the ordinary nail or pin cannot be placed in contact engaging position, either accidentally or on purpose..

In the drawings, wherein similar parts in the several drawings are designated by like numerals, the numeral II) designates the body of an electrical receptacle or plug-in socket formed from a suitable insulating material such as porcelain or plastic and by any usual method. The body has a base II, upturned ends I2 and I3, and an upstanding land portion I4 having therein a well depressed portion I5 with sides It and I1. The well extends to the base II. Centrally disposed at each end are the usual fastening ears or lugs I8, of metal secured to the body of insulating material, and having elongated slots I9, by means of which the receptacle may be attached to the usual outlet box.

Electrical contact elements and 2| are secured to the sides I6 and |1 respectively, and on each contact an attachment screw 22 is mounted so that the contacts may be each attached to current carrying or live wires.

Mounted on raised lugs 23 disposed opposite one another and projecting from each of the side members |6 and |1 for arcuate movement around pivots 24 is a barrier plate or shutter 25 formed from an insulating material such as a suitable plastic or porcelain. The barrier or shutter consists of a cylindrical segment 26 from opposite sides of which segmented arms 21 extend to engage pivots 24. The barrier has two aligned spaced apart slots 28 in the segment 26 into which the prongs 30 of an ordinary electrical plug may be passed. The barrier or shutter is so shaped and proportioned as to be received in lower recess 3| and upper recess 32 formed in each of the side walls |6 and |1 of well 5. The barrier is biased toward the bottom of the slot or recess 3| by two springs 33. The springs are attached to each arm 21. The other ends of the springs are secured to pins 34 on the base Two locking dogs 35 are mounted one on each of the side walls |6 and Il' for angular movement about the pivot pin 36. Each of the dogs 35 has a detent or projection 31, which engages with a shoulder or tooth 38 on each of the segments J 2B. The detent and tooth form a latch to hold the barrier in the lower or locked position. The dogs are urged toward the segment 26 (to the left as seen in Figures 3 and 4) by flat springs 39. A tongue portion 42 projects outwardly from each of the dogs 35 to be engaged by the prongs 30 of the plug as will be described. The upper end of detents 31 and the lower portion of the teeth 38 have sloped portions 40 and 4| respectively so that the barrier when urged to 'locked position by the action of springs 33 after the withdrawal of plug prongs will allow the teeth 38 to slide over the detents 31 until the detents engage the teeth, which occurs when the barrier is in locked position adjacent the bottom of the l lower recess 3 A cover plate 43 is provided with two holes 44 and 45 through which screws may be passed into threaded holes 46 and 41 respectively disposed in the top surface of the land portion i4, to secure the plate to the receptacle. In cover plate 43 are two slots 48 and 49, which are of such length and breadth and so spaced as to accommodate the prongs 30 of an ordinary electrical plug, throughout the movements thereof when the plug is moved from the barrier position to the insertible position Where the plug prongs may be slid into electrical union with the contact elements 2D and 2 When the barrier plate 25 is in the lower position or locked position, it is impossible for an object such as a nail to be pushed into the receptacle so as to engage the electrical contacts 20 and 2|. In this initial position of insertion the plug cannot make electrical connection directly with the contacts 20 and 2|. However, after the insertion of the two prongs of the plug part way into the receptacle the dogs will be released from engagement with the teeth 38 by moving the prongs inwardly (to the right of Figure 3) until the prongs engage and then move the dogs 35 by pressing on the tongues 42. The barrier or shutter 25 may then be moved upwardly from the barrier, locked, or closed position shown in Figure 3 to the unlocked or contact exposed position shown in Figure 4, where the plug prongs 30 may be slid into electrical engagement with the contacts 20 and 2|. At the bottom of each of the contacts is a ledge 50 on which the ends of the prongs rest when in engagement with contacts 2U and 2| This is to prevent any unplanned downward movement of the plug, which movement would tend to take place due to the pull of springs 33 should the engagement be loose. When the plug is withdrawn from the receptacle the barrier 25 is promptly moved to the lower or locked position (Figure 4) by the action of springs 33, and held there by the latching means.

In Figure 6 we have shown an electrical plug which may be advantageously used with our invention. This plug has two metal prongs 60 and 6| which extend outwardly in a straight line for a short distance and are then slanted upwardly and may be arranged as to lie along the contacts 20 and 2 We have shown an exemplary and presently preferred embodiment of our invention, but it is to be understood that changes may be made in the structure Within the scope of the following claims.

We claim:

l. In a plug-in socket structure having a contact element arranged to detachably receive a Contact prong in electrical union, a shutter in the form of a radial segment of a cylinder hinged at the longitudinal axis for arcuate movement and having a slot for passage of a contact prong into the socket to an initial position of insertion out of line with the contact element, the shutter being movable in a limited arc relative to the contact element from the initial position of insertion to a position where the slot is in alignment with the contact element, and means for restoring the shutter to its initial position when the plug is withdrawn, and means for locking the shutter in its initial position.

2. In a plug-in socket structure having a contact element arranged to detachably receive a contact prong in electrical union, a shutter in the form of a radial segment of a cylinder hinged at the longitudinal axis for arcuate movement having a slot for passage of a contact prong into the socket to an initial position of insertion out of line with the contact element, the shutter being movable in a limited arc relative to the contact element from the initial position of insertion to a position where the slot is in alignment with the contact element, means for restoring the shutter to its initial position when the plug is withdrawn, teeth on the shutter, and locking dogs arranged to cooperate with the teeth for locking the shutter in its initial position, each dog having an outwardly projecting tongue engageable by the prongs whereby the locking dogs can be released by insertion of the prong.

3. In a plug-in socket structure having two contact elements arranged to detachably receive the two prongs of an electrical plug in electrical union, a shutter in the form of a radial segment of a cylinder and hinged to move in a limited arc, two prong receiving openings in the shutter, means for locking the shutter in closed position wherein the prongs when passed through the shutter openings are out of electrical union with the contacts, means operable by the insertion of the two prongs for releasing the locking means, and means urging the shutter to closed position, said shutter being arcuately movable from the closed position to a position where the prongs 5 may be moved into electrical union with the contacts.

4. In a plug-in socket structure having two Contact elements arranged to detachably receive two prongs of an electrical plug in electrical 5 union, a shutter in the form of a radial segment of a cylinder and hinged to move arcuately, two prong receiving openings in the shutter, means for locking the shutter in closed position wherein the prongs when passed through the shutter openings are out of electrical union with the contacts, means operable by the insertion of the two prongs for releasing the locking means, means urging the shutter to closed position, and projections on the contacts for preventing the downward movement of the plug when the prongs are in electrical union with the contact elements.

ISAAC MOSES, JR. SHAHADY ESA ALBERT.

REFERENCES CITED The following references are o f record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,119,428 Englar May 31, 1938 2,455,582 Hoessel Dec. 7, 1948 FOREIGN PATENTS Number Country Date 531,281 Great Britain Jan. 1, 1941 684,289 Germany Y Nov. 25, 1939 

